Election districts for the board of supervisors in a Central California county illegally dilute the voting power of Latinos and deprive them of an opportunity to elect candidates of their choice, a federal judge said Friday.

U.S. District Judge Dale Drozd struck down Kern County's 2011 redistricting plan, saying it was not “equally open to participation by Latino voters.”

The ruling came in a lawsuit by the Los Angeles-based Mexican American Legal Defense and Educational Fund against the Central California county. An email after hours to the county's attorney, Mark Nations, was not immediately returned.

MALDEF argued that the boundary between two districts in the county broke up a large Latino community in violation of the federal Voting Rights Act.

“Today's decision should stand as a warning to other counties in California, a number of which also failed to comply with the Voting Rights Act during the last round of redistricting,” Thomas A. Saenz, president and general counsel of MALDEF said in a statement. “The growing Latino community is entitled to representation, and drawing lines to protect incumbents risks costly litigation to secure an eventual remedy to protect voters' rights.”

Lawsuits challenging voting districts in California are unusual. The Obama administration aggressively pursued lawsuits over minority voting rights in Texas and North Carolina, but was criticized for not taking similar action in California. Los Angeles County, where roughly half of the 10 million residents are Latino, has also faced criticism that its political boundaries unfairly reduce the clout of Latino voters.

Drozd's ruling came after an 11-day trial in December that included testimony from Kern County residents, demographers and political scientists and historians. The judge said the plaintiffs had shown that the Latino community in Kern County was sufficiently numerous and geographically compact to constitute the majority in a second supervisorial district, and that the majority in Kern County votes sufficiently as a bloc to usually defeat Latino-preferred candidates.

The lawsuit will now move into a second phase for the judge to consider ways to correct the imbalance.